Running an intel 20" imac, bone stock - that means 2ghz core duo with a radeon mobility x1600. I'm running the latest signed catalyst mobility drivers straight from ATI. I've also tried the drivers that apple provides with the boot camp 1.1 driver disc as well as the 6.2 based omega drivers - all of them have the same issue.

When I shoot a mutagen container and enter the green cloud, the framerate drops to one to two seconds per frame. I did not typo that. When the effect drops, everything returns to normal speed. Running in dx7 mode works, but I'd like to think the radeon x1600 is a dx9 part.

Has anyone seen this issue before? I know it's unrelated, but Oblivion has the same issues with oblivion gates and whatnot whenever a refraction shader is in use - same slowdown happens at the start of HL2:E1 with the vortigaunts. Again, refraction shader completely kills my framerate.

Display drivers: Passed
There were no problems with the display drivers you are using.
You should still check for updated drivers, which are available here
Display Adapter: ATI Mobility Radeon X1600
Display Version: 6.14.10.6626

DirectX: Passed
Your version of DirectX meets the minimum requirements

Background Processes: Passed
There were no processes found that conflict with Steam or the games.

Loaded Modules: Passed
There were no loaded modules found that conflict with Steam or the games.

Services: Failed
The following services were found on your system. Please try disabling the service or uninstalling the application assoicated with them, and see if that resolves your issue
Service: Ati HotKey Poller
Ati HotKey Poller has been reported to cause mouse and keyboard lag.
Severity: Low

Layered Service Providers: Passed
There were no LSPs found that should conflict with Steam or the games.

Audio/Video Codecs: Passed
There were no audio/video codecs found that conflict with Steam or the games.

Additional Information

If Steam continues to crash, try deleting all files and folders in the Steam directory except for steam.exe and the SteamApps folder

If you continue to have problems playing the games, try using the launch options -nosound and -windowed.

Open Steam, then Play games
Right click the Souce game, click properties, then Launch options
add -nosound -windowed, click ok, then close.

If you continue to have problems updating Steam, please exit from Steam, and then delete the following files from your Steam directory.